Gyrocompass



y 5, 1947= R. HA SKINS, JR 4 GYRO COMPASS Filed April 29, 1945 2 Sheets-Sheet 1 I TRANSMITTERI HASKINS JR;

. II m o M E I A 62 5 B 4%. 3 m K W m Lg :7 Mm 6 6 v O w mo 5 2 H m l LM. 7 m M 1 2 3 O 5 7 8 .w 2 4 w 4 5 2 JIM 75 0 a v M ew" F 0 I w u a a m w I. \\w m m F May 6, 1947. R. HASKINS, JR 2,419,948

GYRO' COMPASS Filed April 29-, 1943 2 Sheets-Sheet 2 a FIG.2

27 32 FIG.4 50 W as as up 5 53 Y m -#E 24- 25 3| GRAVITYTORQUE GYRO MOTOR FIG.5

SWITCH SWITCH 4 DAMPING TORQUE M OTOR lNVENTdR ROBERT HASKINS,JR.

Patented May 6, .1947

' "Robert'Haskins; JrQiGardenUityrN: Y,,-'assigiior If to perry Gyroscope Companyflnc a corpora- '--'tion ofNew-York 1 -fApp1icationApriL29, 194$,sermrmp4sdo71 lfWhile-the gyroscopie compass has come into ide see rs ins hi hm at mp r i moderate; speeds, it has so: far not proved acceptable; for aircraft whichtravelzatmuch greater veecity an ra sio t the faCUhQ/B aey p o p s a man kn ed e t e v all forms offmagneticcompasses. The principal object ofthe present invention is to overcome oertain limitations oftheegyro'compassto enable it to-.b e; successfully employed onaircraft and other highspeed. craft. "For this; purpose, I propose to greatly reduce thesettlingwime or a standard gyro compass, which is onthe orderof :85 minutes, so that if displaced from the meridian it will quickly return thereto; since on high speedoraft an .error whichipersists for zoverian hour would cause a-serious' deviation from course; However, inforder that the spin axismay move from its cor.- reet positionon the virtual meridian forw onesneed andheading'of'the craftto, its new correet :position for :a changed speed or heading ofthe craft, it, isenecessary. that a torque be exerted; 0115213116 compass during the change,;sufiioient tomove'it to the new correct-position by the time thehhange is completed. It is -known; that this condition-is satisfieclronly if the undamaged period'of: theicompass is approximately where-R is the radius "of the earthand g isthe acceleration :of :gravity, for that particular latitude. This; correct value ofthexperiod varies slightly from -.'e'ighty -five-t minutes, depending 'lupon ?;the latitude. :I rproposeptherefore; to rcon'struetflmy improved -oompa'sszwith awariable'.or'multiperiod offoscillation, the? "normal period being aaishort period of a. few mifiutesisay 5.to 10 minutes; and changing overtoior introducingaautomatioally a long :period: of a'bout- 1 85-; minutes "whenever :a change ottspeed'sorscoursrtakesplace.

.01616 of the objects of the present invention, therefore, is to provide a variableror multiperiod gyro compass or. an instrument of this character that normally operates on a period of a; fewminutes is controlled to. change to a conventi'onal longperiod when afieoted by acceleration.

A" ieat re of.tthejiinilention resides in; the prov s on; 91" n s le e e l' pns 'fmee s q el'ianging the torque:appiiedperidegr of tiltof thegyro compassto alterthe period of tl' e inemi ent-1mm sjshort'toa long ,perio'd=during;ac--

' I; pass jfthat is, 'thetorqu'e usuallyterrnd.theigiavi- 17 Claims' (Cl. 33'-'2 26) c'eleration.

' Another feature of j the invention [consists in provision of a means for i"edi1cing interardiiial errors. in the compass, that is, errors due tofrolling or pitching of the .craft' on'which it is mounted.

II, propose to accomplish thislpurpose' byfterngm rarily: eliminating, or reducingithetorque 111Gb imparts meridianaseeking properties ofjthe com-* tationaltorque," during the times when-the trunnion axis of the'compass is tiltedfont .ofthe'horizontal' plane or, in other-words; is tilted aboutthe' north-south axisinthei'E -wiplane. fiBy eliminat ing such "torque at this time, interdardinaljerrors aregreatly reduced. t 0 her objects, features and structural details of the" invention will be apparentifrom' the. followd iption When"read in relation to jthej accomr a 'iyin 'drawing. wherei Fig.1 is. a" side elevation of a gyro compass cons u t c rdancewith the present'invent on. iththe; casing of the samelshown'insection;" Fig. 2 'is ai "diagrammati'0 view ofthejt ransmit ter end receiver jcom ass {repeater arrangement controlled by the gyroeompass; (Fig; 3 is a detailed sidefel'evationof thepickofi employed to governthe;1131103???v p m'otor;

"Fig. .4 is a schematic fwiiineidi 'iiainjshjowing thlmafiner in; which the phantom" iEifigjmotQIfliS controlled; 7 Fig.5 is a diagrammatic view. 'showingftheimprovedcircuit "for controlling ithelj'pfejriod. ff'the gyro compass; v Fig; is 'al d'etaiilfillh View of Ith liwitcl'llshown inl'Fig. .1. on'the top or theirttdribeafine'caseor the instrument; T'Fig. T '1 is a "rerticaliiero's's s'eetion of the-1f switch shown in"Fig.6; 'fFigZ SI'is .a schematic firiwfls'ho i fi gthe tinie .de lay control switch T that is? responsive to linear fac: celera'tionshaving'iaijcoifiiioheflt. inla .NZS plane; ].'Fi'g. .9 is fa tdetail"'frofitnlevation. .o'f th ,.,normall'y .olosed, switch" that isf-rspohsiire to an ular 1 yelocity about a'veftical'axigand ing or binnacle ID that is universally mounted by means of gimbal ring H and yoke 12 upon a base 13. Casing I9 is pendulously supported in its universal mounting. A phantom or follow-up ring I4 is rotatably mounted within the enclosing casing ID by upper and lower bearings respectively indicated at [5 and I6, journaling shafts l5 and I6, respectively. These bearings and shafts define a vertical axis about which the hantom ring is oriented in a conventional manner from the sensitive element of the compass. The azimuthal position of the ring is employed in the present instance to position the rotor of a Selsyn transmitter generally indicated at IT. The sensitive element of the compass comprises a vertical ring l-B mounted for rotation within the phantom ring H by means of suspension wires 29, 2! and guide bearings 22 and 22'. Rings l4 and {8 are coaxial and angular displacement therebetween is 1 effective to control a motor 23 that operates in a conventional manner to cause the phantom to follow the vertical ring in azimuth.

The provisions made to carry out this function in the present instance, as shown in Figs. 1, 3 and linclude an electromagnetic ,E, pick-off having an armature 24 fixed to the bottom of the vertical ring 8. The other element of the pickoff is mounted on the phantom ring l4and' consists ofv a permeable core having three pole pieces 25, 26 and 21. The central leg or pole piece of the pick-off has a winding 28 thereon which is energized from a suitable A. C. source 30. The outerlegs or pole pieces 25 and 21 have opposed windings 3i and 32 thereon so that a phase sensitive signal is obtained therefrom in accordance with the direction of departure of the rings l4 and i8 from their normal relative position in azimuth. When armature 24 covers equal portions of the outer pole pieces, no signal is derived from the pick-off. The signal of the pick-off is amplified by a suitable phase sensitive amplifier 33 and is fed to the reversible motor 23 whose shaft.34 moves the phantom ring l4 by way of gears 35 and 36 to restore the rings l4 and I8 to a properly oriented relationship in which there is no angular displacement therebetween.

The directional reference supplied by the instrument is obtained from the phantom ring which in this instance positions the rotor 31, Fig. 2 of the Selsyn transmitter 11. The Selsyn receiver 38 has a rotor 39 that positions a compass card 40 of a repeater compass in a manner well-known in the art. Suitable compass corrections may or may not be introduced in the repeater readings. If such corrections are desired, a corrector 43 may be employed equipped with settings for speed S, heading H and latitude L of the craft. As this invention is not concerned with this device, no details are shown.

With further reference to Fig. l, the improved gyro compass furtherincludes a rotor bearing case 44 which is pivoted within the ring '18 for freedom about a horizontal axis in a conventional manner such as by means of the bearings 45 and 46 which normally lie E-W. The gyro rotor (not shown) is mounted within the case 44 in a conventional manner, the spin axis of the rotor normally lying N-S and being normal to the plane of the paper in the showing thereof in Fig. 1. The gyro motor may be electrically spun by a suitable motor (not shown) whose stator windings 41 may be supplied with A. C. electrical energy from source 48', as particularly shown in Fig. 5.

In accordance with the teaching of the present 4. invention, both a damping and gravitationally responsive or meridian seeking torque exerting means are employed, said torques normally having a substantially fixed ratio to one another at the shorter of the two periods at which the compass functions. For the short period, this ratio may be chosen to give normal or somewhat greater than normal damping. In the present instance, separate motors are employed to function in this relation, the gravity torque motor 48 and a damping torque motor 49. The motor 48 imparts meridian-seeking propertiesto the compass and therefore acts in place of thetorque usually exerted directly by gravity, and I therefore usual 1y refer to it herein, for the sake of brevity, as: the gravity torque motor. It acts to exert a torque about the horizontal axis of the rotorcase of the instrument. The damping torque motor 49 iseffective to exert a torque about the axis of the vertical ring l8. The torque motorsemployed may be of the conventional squirrel.

cage induction type having a wound stator and; an inductive rotor in each instance. The stator- 50 for motor 48 is suitably fixed to one of the inwardly disposed side faces of the vertical ring.. The inductive rotor 5| of this motor is mounted. on a bracket 52 located on the case 44. Thestator and rotor for motor 49 are respectively indicated at 53 and 54. Stator 53 is mounted on the ring I8 at the base portion thereof and rotor- 54 is fixed to the phantom ring M. The stators: of the respective motors are preferably two phasewound. As shown in Fig. 5, winding 55 of motor 48 and winding 55 of motor 49 are continuouslysupplied with energy from the source of energy 48'. The control windings 51, 51 of motor 48 and similar windings 58, 5B for motor 49 are included in the novel gyro compass control circuit.

This circuit includes means for producing a signal responsive to tilt of the rotor case of the gyro compass in the form of an E pick-off of the general character previously described in connection with Fig. 3. In this instance, the pick-01f generally'indicated at 60 has a curved armature 6| mounted on one of the trunnions of the rotor case 14. The three-legged magnetic core 62 (see Fig. 5) of the pick-off depends pendulously from the horizontal axis of the case on pendulous plate 16 and thus provides a vertical reference for the instrument. The windings for the pick-off are similar to those previously described, the pick-off providing a phase sensitive signal output that is utilized to energize the control motor windings 51, 58 or 51, 58' of both motors 48 and 49 to obtain the gravity and damping torque necessary to maintain the spin axis of the gyro compass in a N-S plane and free of tilt. The foregoing pick-off is shown more in detailin Fig. 6 of the copending application of J. C. Wilson and O. E. Esval, Serial No. 463,286, for Transformer pick-off, filed October 24, 1942. An amplifier 63 may be employed to amplify the signal output of the pick-off 60.

When no acceleration is present, i. e., when the ships course and speed remain constant, the full amplified output of the'pick-ofi is available to directl control the gyro compass. The relatively large gravity and damping torque then available provides a gyro compass with a relatively short period, say'on the order of a few minutes, for example, 501' 10 minutes. To change the period of the gyro compass from short to long as acceleration occurs (which latter period is preferably the standard period or about cares-4s :stated), :I providein :the rcontrol circuit ;a noranally by-ipassed resistor zfifl-svhich-whenuinrcircuit, reduces the strength of the signal orrcontrolacurirent suppliedz-tothoth torqneiexerting means when :itnsnncluded relationfin the=.circuit. .As shown in Fig. 55, resistor 154 :shunts :two normally 'lclosedswtitchesdesignated generally by themespectivemeference numbers 65 and 66. :Both "switches fiaand 55 are responsive .toacceleration ato change the :controlling circuit for the torque ;motors to include the. resistor 164 therein, ,-=one .-switch':65 .:being' responsive tto acceleration due to turns land :the other, :66, :to that due ,:to :speed changes. By this arrangement, which would -1eave:the ratio of thexmeridian-seeki-ng to the damping :torqne unchanged, Tit :may he demonstrated either mathematically :or experimentally that the percentageidamping is greatly'decreased, which :resultfi-is idesirableibecause :du ing :turns'or change in speed' the damping;factor causes an :errorlin ithecompass, :as .has longbeen recognized thezart. A 'As particularly ishownzin Figs. 1. and :9, 1 switch 5 -comprises a movable Lorin-16.! "that .moves off the connecting: segment 68=1mder oontrolofa turn responsive device .ioperated by :movement of the craft about a vertical axis. The :device provided in the present instanceis amatea-cf'tum gyro that ismoun-te'd in a baseplate .69 on the bottom of the casing it. This gyro device, Which'is of conventional construction, includes a spring centralized oearing ring .m and gyro rotor H that is preferably driven by ea :motcr (not shown). Thespin axis. Qf the rotor i and theaxis of rin 19 are normally horizontal, the gyro precessing about its axis responsive to. turning "movement of=the craft about its :verticalaxis to swing the switch arm 6] so .that the :same breaks contact with segment '68. This :switch isthereforeresponsive to-acceleration forces realised by .tur ing or change of course.

In Fig. 8 I have shownraz-switch responsive to acceleration forces due to'chnngeof speed havin an NsFS' component. 'Switch 66 comprises an :altern atin'g current delayedactionr relay J 2 whose armature T3 is spring -pressed against contact 1'4. Such delayed action relays are well known in thetrade. Thecoil is energized by al ick-off similar in construction .to;.pick-oifi6il. Mounting plate orpendulum .16 is employedfor both pick-offs l5 and 'iiil in this'instancaias shown in Fig. 1. The pendulum is responsive to any linear accelerationxhavingacomponent in a N-S :plane, such-.asidue toaa change ofspeedin the N-S direction, and if the resulting movement thereof is of suflicientmagnitude and duration, a signal is produced by the .pick-ofi' toefiect the operation of the relay l2. Relay '12 functions as a time delay control of the switch that is not responsive to' momentary fluctuations in the output for the controlling pick-off '15, due'to rolling and pitching, which have aquick period.

'I preferalso'to provide a'means'for'reducing intercardinal rolling 'error, sometimes referred to as quadrant'al error, in my-improved compass, for'which purpose Iinclude in thecircuit-a-nor- *mally closed-switch ll (Figs. '6 and 7) thatlis re- "sponsive to "oscillatory motions about the :N-S axis-(i. e., responsiveto'tiltof the trunnion axis d545 out of the horizontal-in the E-Wplane) to cause the torque motors to be effective only when the :craft'is substantially horizontal. It

will'be understood that when the rotor case is swung back-and forth during :rolling or pitch- .ingr movements-br ttle" craft,.giving rise'to violent accelerations, r when sthe trunnion axh $5 .45 itilted ithroughea substantialtangla switch 11 .is efieotive .to momentarily, open the control circuit. lihe means employed toeper'fonn this ition renders :the control signal .in'efiective when the gyrorcom-pass isrooked :dlle tothe oscillatory motions of the -cra-ft. Elie -:pha.Se displacement between the position of the entire spendulouaas- .sembly and :the .='bubble in the switch causes the bu bble :tonbe rdisplaced f-rom equ'ilibrium when the oscillatory acceleration is a maximum. As particularly shown in .-Eigs.;6 and 7,-the meanspro- "vided-is a-switch of theliquid leveltypewhose instriated; casing 18 %is situated on top ;of therotor bearing -oase M. The {liquid enclosed withidthe case as indicated-at 19 .is current conducting and *the -.bubble 1-9 stormed therein :moves responsive to tilt :of the switch to cover one or the other of the conducting contactstll and 1-81 and effectively reduce the current flowing through the switch. The contacts in this instance .=are.normally--sitmuted .E-W in .a horizontal plane so that the switch is responsive to rolling o1'- pitching inovemerits of the instrument aboutthe-N-S axis,i..-e., toztilt ofthe;.trunn-ion-aX-is Afi-fli, which always 'lies E-W. switch is consequently effective to reduce the -torque motor control of the the compass .at periods of disturbing accelerations, or whenever the trunnion :axis is inclined Land thus minimize the intercardinal rolling .error.

'While, as above explained, the percentage damping is reducedat' the .time-the' ship changes course or speed, 11 ,find it preferable to .entirely eliminate the damping at this time. In .other words, -I prefer to employ a damper only when .the compass is operating .on 'the short period. :Such a modification is :illustrated in :the modified form cfcircuit shown ;in Fig. .10, wherein the torque motors 48 .and 49 are arranged so that .the s-witches 5 and-66 renderithe damping torque motor ineffective, responsive to acceleration and simultaneously efiect the necessary reduction inthe strength of-the currentsupplied to the gravity ,torquexmotor. .In this arrange- .ment switches -65 and .66 which are controlled in the manner previously described, are formed with two poles instead'of one. As shown, the control circuit'for thegravity torque-motorfia includes the parallel arranged resistor 64 and two 10f .the;series connected poles -65 and #86 orthe :.modified'switches:fi5 anduBB. When the switches '65 .and66 are intheir=normal closed position, -thezcontrol signal for the gravity torque motor AB-shunts the resistor 64. The poles 87 and'f88 ofithezswitch are in a second circuit whichim cludes the damping torque motor 49. Normally 'Ipoles 81 and 88 are in the closed position so that the circuit through the damping torque motor iscompleted. The respective double pole switches 65 and 66 are effective'intl'n instanceto reduce the control current supplied to the gravity torque motor and .to'open the circuit containing'the damping torque motor.

:As'many .changes'couldbemade in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it :isintended that all matter containedin the above description or shown inthe-accompanying drawings shall beinterpreted .as illustrative and notin a limiting sense.

What is. claimed is:

.1. ;A variable period .gyro compass having a :gravity torque exerting means, a damping torque -.:exerting means xneans. provid ieontl'ol esigfill for both said gravity and damping torque exerting means responsive to tilt of the rotor case of the gyro compass, circuit meansoperable to simultaneously reduce the amplitude of the control signal to the gravity torque means and render the damping torque means ineffective, and acceleration responsive means for controlling said circuit means.

2. A variable period gyro compass having a gravity torque exerting means, a damping torque exerting means, means responsive to tilt of the rotor case-of the gyro compass ior producing a signal, circuit means controlling said gravity torque exerting means and said damping torque exerting means from said signal, a normally in effective auxiliary circuit for reducing the strength of the signal current fed to said gravity torque exerting means, and acceleration responsive means simultaneously operable to render said auxiliary circuit effective and to open the circuit to said damping means.

3. A short period gyro compass for dirigible vehicles having a normally effective damping factor, a gravity-actuated tilt detecting means, means controlled thereby for applying a meridian-seeking torque on the compass such as to give the compass normally a period of a few minutes, and a common means operative during turns for substantially eliminating said damping and for reducing said torque sufficiently to lengthen the period of the compass to approximately 84 minutes during turns.

4. A dual period gyro compass having a normal period on the order of a few minutes and a secondary period on the order of one and one-half hours, a transient damping means for said compass, and means for rendering said damping means operative only during the time the compass has the shorter period.

5. A dual period gyro compass having a normal period on the order of a few minutes and a secondary period on the order of one and one half hours, means for changing the-compass from its normal to its secondary period, and means responsive to turn of the craft for bringing said first means into action. a

6. In a gyro compass having a rotor bearing frame mounted for freedom about a vertical and a normally horizontal EW axis and a rotor journaled therein with its spin axis normally lying horizontal and N-S, means responsive to tilt of said spin axis about said E-W axis, means controlled thereby for exerting a meridian-seeking torque on said frame, means for detecting tilt of said E-W axis out means responsive to said last-named tilt detecting means for temporarily eliminating said torque during such tilt.

7. A variable period gyro compass having a rotor case mounted for freedom about a vertical and a horizontal axis and a gravity and damping torque exerting means for said compass, means providing a signal controllingsaid torque exerting means and responsive to tilt of the rotor case about said horizontal axis, and means for changing the amount of the torque exerted by said torque exerting means per degree of tilt of the compass to vary the period of the compass.

8. A gyro compass having a rotorcase mounted for freedom about a vertical and a'normally horizontal E-W axis and a gravity torque exerting means for said compass for impartingmeridian-seeking properties thereto responsive to tilt of the rotor case about said E-W axis, and

means rendered effective by tilt about a N-S of the horizontal, andaxis or accelerations having an E-W component for temporarily rendering ineffective said torque exerting means.

9. Means for electrically controlling a gyro compass comprising an energy source, means supplied by said source for producing a. signal responsive to tilt of the rotor case of the gyro compass, a circuit including said signal producing means, a gravity torque motor normally controlled from said signal means, and means rendered effective by tilt or lateral acceleration of the rotor casing in the E-W vertical plane or direction for temporarily eliminating the control of said motor from said signal.

10. Means for electrically controlling a gyro compass comprising an energy source, means supplied by said source for producing a ignal responsive to tilt of the rotor case of the gyro compass, a circuit including said signal producing means, a gravity torque motor and a damping torque motor normally controlled from said signal means, and means rendered effective by tilt of the rotor casing in the E-W vertical plane for temporarily eliminating the control of said motors from said signal.

11. Means of the character claimed in claim 10, in which said last named means is a liquid level switch mounted on the rotor case of the gyro compass with its contacts positioned in the E-W plane.

12. A dual period gyro compass as claimed in claim 10, having a normal damper and means likewise responsive to change of speed or course for rendering said damper temporarily inoperative.

13. A dual period gyro compass having 9. normal period on the order of a few minutes, means for temporarily altering said period to a secondary period on the order of one and one-half hours, and means responsive to change of speed or course of the vehicle for bringing said firstnamed means into operation.

14. A variable period gyro compass for vehicles having a gravitationally controlled torque-exerting means normally adapted to exert a strong torque and intermittently adapted to exert a much weaker torque, means providing a control signal for said torque-exerting means responsive to tilt of the rotor case of the gyro compass, and means rendered efiective by acceleration of said vehicle for temporarily altering the torque normally exerted by said gravity means from strong to weak, whereby the period of the gyro compass is normally a few minutes, but during acceleration becomes substantially minutes.

15. Means for electrically controlling a multiperiod gyro compass comprising an energy source, means supplied by said source for producing a signal responsive to tilt of the rotor case of the gyro compass, a circuit including said signal producing means, a gravity torque motor, a damping torque motor controlled from said signal, means in the circuit between said signal and motors for temporarily decreasing the torque of at least the gravity torque motor for any given signal strength, and acceleration responsive means for and said motors, and an EW r011 responsive, normally closed switching means shunting said impedance, whereby the impedance is effective to normally reduce the torque exerted by the motors during EW rolling of the compass.

1'7. .As a means for reducing rolling error in gyro compasses, the combination with a gyro compass having a gravitationally responsive torque-applying device for imparting meridianseeking properties, means mounted on said compass for detecting and producing a signal upon tilt or roll of the compass in the EW plane, and means responsive to said signal for temporarily eliminating such gravitational torque during such tilt.

ROBERT HASKINS, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,686,524 Hight Oct. 9, 1928 1,773,411 Thompson Aug. 19, 1930 1,628,136 Ford May 10, 1927 1,777,601 Brown Oct. 7, 1930 1,773,412 Thompson Aug. 19, 1930 FOREIGN PATENTS Number Country Date 255,745 British July 29, 1926 Certificate of Correction Patent No. 2,419,948. May 6, 1947.

ROBERT HASKIN S, JR.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 1, line 26, for undamaged read undamped; column 5, lines 43 and 44, for havin an read having an; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 12th day of August, A. D. 1947.

LESLIE FRAZER,

First Assistant G'ommz'ssioner of Patents. 

